It didn't do what I thought it did with a RevertableProperty; it always
returned Nothing because even if the input properties to <!> are NoInfo, it
casts them to HasInfo.
Even if it had worked, it lost type safety. Better to export the
Property NoInfo that is used in a RevertableProperty, so it can be used
directly.
* Property has been converted to a GADT, and will be Property NoInfo
or Property HasInfo.
This was done to make sure that ensureProperty is only used on
properties that do not have Info.
Transition guide:
- Change all "Property" to "Property NoInfo" or "Property WithInfo"
(The compiler can tell you if you got it wrong!)
- To construct a RevertableProperty, it is useful to use the new
(<!>) operator
- Constructing a list of properties can be problimatic, since
Property NoInto and Property WithInfo are different types and cannot
appear in the same list. To deal with this, "props" has been added,
and can built up a list of properties of different types,
using the same (&) and (!) operators that are used to build
up a host's properties.
Joey Hess
Joey Hess
Joey Hess